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Abstract:

According to one embodiment, a decolorizing device includes a first
stacker to stack sheets to be decolorized images on the sheets, a second
stacker arranged adjacent to the first stacker, wherein the sheets
stacked on the first stacker is kept waiting on the second stacker in
order to be decolorized the images, a pressing unit to urge the sheets
stacked on the second stacker downward and keep the sheets stacked on the
second stacker flat, an image decolorizing unit to decolorize the images
on the sheets, and a sheet feed unit positioned on an upper surface of
the pressing unit to convey the sheets pressed on the pressing unit from
the second stacker to the image decolorizing unit.

Claims:

1. An decolorizing device comprising: an image decolorizing unit to
decolorize an image on a sheet; a judging unit to determine whether the
sheet decolorized by the image decolorizing unit is reusable or not; a
sheet stacker to stack the sheets decolorized by the image decolorizing
unit; and a conveying unit to convey the sheet to the sheet stacker, the
conveying unit arranging the reusable side of sheets determined to be
reusable only one side of the sheets in the same direction.

2. The decolorizing device according to claim 1, wherein the sheet
stacker includes a first sheet stacker to stack the sheets determined by
the judging unit to be reusable only one side of the sheets and a second
sheet stacker to stack the sheets determined by the judging unit to be
reusable both sides of the sheets.

3. The decolorizing device according to claim 2, wherein the conveying
unit includes a reversing path to reverse the one side reusable sheets.

4. The decolorizing device according to claim 3, wherein the sheet
stacker includes a third sheet stacker to stack the sheets determined by
the judging unit to be nonreusable.

5. The decolorizing device according to claim 4, wherein the image
decolorizing unit heats the image formed with erasable image forming
material more than decolorizing temperature in which the color of
erasable image forming material disappears.

6. A method for controlling a decolorizing device, comprising:
decolorizing an image on a sheet by an image decolorizing unit;
determining whether the sheet decolorized by the image decolorizing unit
is reusable or not; and stacking the sheets determined as reusable only
one side of the sheets to be arranged in the same direction of the
reusable side of the sheets.

7. The method according to claim 6 further comprising: stacking the
sheets determined to be reusable only one side of the sheets in a first
sheet stacker; and stacking the sheets determined to be reusable both
sides of the sheets in a second sheet stacker.

8. The method according to claim 7, wherein the one side reusable sheets
are reversed while the one side reusable sheets are conveyed in a
reversing path.

9. The method according to claim 8 further comprising: stacking the
sheets determined to be nonreusable in a third sheet stacker.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/832,686, filed on Jul. 8, 2010, which is based upon and claims the
benefit of priority from: U.S. provisional patent application No.
61/226,639, filed on Jul. 17, 2009; and U.S. provisional patent
application No. 61/226,626, filed on Jul. 17, 2009, the entire contents
of each of which are incorporated herein by reference.

[0002] This application is also based upon and claims the benefit of
priority from: Japanese Patent Application No. 2010-38331, filed on Feb.
24, 2010; and Japanese Patent Application No. 2010-116009, filed on May
20, 2010, the entire contents of each of which are incorporated herein by
reference.

FIELD

[0003] Exemplary embodiments described herein relate to a decolorizing
device for decolorizing an image formed on a sheet by an image forming
apparatus and accumulating the sheet from which the image has been
decolorized, and also relate to a method for controlling the decolorizing
device.

BACKGROUND

[0004] More sheets are consumed as the amount of various kinds of
information increases. On the other hand, sheets are recycled in order to
save the resource of sheets. For example, in recycling of sheets, used
sheets having image information thereon made of toners and the like are
processed using a large amount of bleaching agent and water, and thus
recycled sheets are manufactured. Therefore, the recycling of sheets
brings about the increase in the cost of recycles sheets, which
diminishes the cost effectiveness and may incur new environment pollution
resulting from treatment of waste water used during regeneration of used
sheets.

[0005] In view of the above circumstances, a technique has been recently
developed to greatly reduce the amount of actual use of sheets. According
to this technique, erasable image forming material made of resin,
pigment, color fixing agent, erasing agent, and the like is used to form
an image on a sheet. This formed image is decolorized from the sheet by
an image decolorizing device, and a white sheet is obtained. This white
sheet from which the image has been decolorized is reused multiple times.
According to this technique, the overall cost relating to reuse of sheets
can be reduced.

[0006] For example, an image forming apparatus having an image
decolorizing function for decolorizing color of image forming material by
heating a sheet and capable of preventing misuse of a reused sheet has
been known.

[0007] The above-described image forming apparatus has not only the image
forming function but also the decolorizing function for decolorizing an
image by heat. In addition, a detecting sensor is used to detect whether
a mark indicating reusable sheet is attached to a sheet or not.
Therefore, even when a user stacks both of reusable sheets and
nonreusable sheets on a sheet feed tray in a mixed manner, the image
forming apparatus can distinguish the reusable sheets. That is, the image
forming apparatus performs image decolorizing processing on sheets
attached with the mark indicating reusable sheet, and does not perform
image decolorizing processing on sheets without the mark.

[0008] However, in the above-described image forming apparatus having the
decolorizing device, if the decolorizing device is feeding sheets placed
at an insertion opening in order to perform decolorizing processing on
previously-inserted sheets when the user tries to perform decolorizing
processing, the user is unable to insert sheets even though the user
tries to feed sheets to perform new decolorizing processing on the
sheets. In other words, in the case where the image forming apparatus has
only one stacker for stacking sheets which are to be subjected to
decolorizing processing, the uppermost sheet of stacked sheets is fed
into the image forming apparatus while decolorizing processing is
performed. Therefore, during the feeding operation, the user is unable to
place sheets on the stackers. In addition, in the case where the placed
sheets are fed in order from a feeding opening, there is a problem in
that only the upper portion of the placed sheets are always reused
repeatedly, resulting in low recycling efficiency. Still more, since
sheets processed by the decolorizing device are already-used sheets, the
sheets could be curled. When the sheets are curled, there is a
possibility that the sheets are jammed during feeding operation and the
processing cannot be carried out smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a schematic diagram illustrating a decolorizing device
according to the present embodiment;

[0010]FIG. 2 is a diagram illustrating operation of a sheet transfer unit
according to the present embodiment;

[0011]FIG. 3 is a diagram illustrating the sheet transfer unit according
to the present embodiment when a partition wall is closed;

[0012]FIG. 4 is a diagram illustrating the sheet transfer unit according
to the present embodiment when a partition wall is open;

[0013]FIG. 5 is a diagram illustrating the sheet transfer unit according
to the present embodiment when a first stacker and a second stacker are
joined with each other;

[0014]FIG. 6 is a diagram illustrating the sheet transfer unit according
to the present embodiment when the first stacker has moved downward;

[0015]FIG. 7 is a diagram illustrating the sheet transfer unit according
to the present embodiment after sheets has been transferred;

[0016]FIG. 8 is a diagram illustrating the sheet transfer unit according
to the present embodiment when the first stacker moves upward;

[0017]FIG. 9 is a diagram illustrating the second stacker according to
the present embodiment when the uppermost sheet stacked on the second
stacker is not in contact with a pressing unit;

[0018] FIG. 10 is a diagram illustrating the second stacker according to
the present embodiment when the uppermost sheet stacked on the second
stacker is in contact with a pressing unit;

[0019]FIG. 11 is a top view illustrating a pressing face according to the
present embodiment;

[0020]FIG. 12 is a top view illustrating a pressing face arranged with a
plurality of cutout portions for a pickup roller according to the present
embodiment;

[0021]FIG. 13 is a diagram illustrating a conveyance path for a sheet
which is judged to be nonreusable by a first judging unit according to
the present embodiment;

[0022]FIG. 14 is a diagram illustrating a conveyance path for a sheet
both sides of which are judged to be nonreusable by a second judging unit
according to the present embodiment;

[0023]FIG. 15 is a diagram illustrating a conveyance path for a sheet
both sides of which are judged to be reusable by the second judging unit
according to the present embodiment;

[0024]FIG. 16 is a diagram illustrating a conveyance path for a sheet
only the front side of which is judged to be reusable by the second
judging unit according to the present embodiment;

[0025]FIG. 17 is a diagram illustrating a conveyance path for a sheet
only the back side of which is judged to be reusable by the second
judging unit according to the present embodiment; and

[0026]FIG. 18 is a control block diagram illustrating a decolorizing
device according to the present embodiment.

DETAILED DESCRIPTION

[0027] In general, according to one embodiment, there is provided a
decolorizing device including: a first stacker to stack sheets to be
decolorized images on the sheets; a second stacker arranged adjacent to
the first stacker, wherein the sheets stacked on the first stacker is
kept waiting on the second stacker in order to be decolorized the images;
a pressing unit to urge the sheets stacked on the second stacker downward
and keep the sheets stacked on the second stacker flat; an image
decolorizing unit to decolorize the images on the sheets; and a sheet
feed unit positioned on an upper surface of the pressing unit to convey
the sheet pressed on the pressing unit from the second stacker to the
image decolorizing unit.

[0028] The best embodiment of the decolorizing device will be hereinafter
described in detail with reference to the attached drawings.

[0029] According to the present embodiment, a sheet transfer unit 101 is
arranged with two stackers 200 and 201 for stacking sheets, and a
partition wall 202 is arranged between the two stackers. This structure
allows a user to add sheets P to the first stacker 200, even while sheets
P are being fed from the second stacker 201 in order to be subjected to
decolorizing processing. Further, a pressing unit 203 is arranged on the
upper surface of the second stacker 201. Even when a reused sheet P is
curled, the pressing unit 203 is urged upward by the sheet P, so that the
sheet is kept flat.

[0030]FIG. 1 is a schematic diagram illustrating a decolorizing device.
The decolorizing device 100 is adapted to heat an image formed on a sheet
with erasable image forming material made of resin, pigment, color fixing
agent, erasing agent, and the like, thus returning the sheet back to
white.

[0032] The user can stack sheets P to be reused on the first stacker 200
exposed to the outside of the decolorizing device 100. When all the
sheets P on the second stacker 201 are transferred toward the image
decolorizing unit 106, and the second stacker 201 becomes empty. At this
occasion, the sheet transfer unit 101 can convey the bundle of sheets P
on the first stacker 200 from the first stacker 200 to the second stacker
201.

[0033] The sheet feed roller 102 is constituted by a pair of driving
roller and a driven roller. The sheet feed roller 102 feeds sheets fed
from the sheet transfer unit 101 in order to have the sheets subjected to
decolorizing processing.

[0034] The first judging unit 103 is constituted by an ultrasonic sensor
103a and a sheet thickness sensor 103b. Before a sheet P is subjected to
decolorizing processing, the first judging unit 103 judges whether the
image on the sheet P can be decolorized.

[0035] The ultrasonic sensor 103a emits an ultrasonic wave to detect
multi-feeding. The ultrasonic sensor 103a detects an air layer between
sheets when multiple overlapped sheets P are conveyed. In other words, an
ultrasonic wave is emitted, and when an air layer is detected, this means
that multiple sheets P are overlapping.

[0036] The sheet thickness sensor 103b detects the thickness of a sheet P.
For example, the sheet thickness sensor 103b detects multi-feeding, a
folded sheet P, a torn sheet P, a staple, and the like. In other words, a
sheet P having an abnormal thickness is inappropriate for reuse, and
accordingly, the sheet thickness sensor 103b judges that the sheet P is
nonreusable.

[0037] The switching gate unit 104 switches the conveying direction of the
fed sheet P. For example, when the first judging unit 103 judges that a
sheet is reusable, the switching gate unit 104 chooses a conveying path
to image decolorizing processing. On the other hand, when the first
judging unit 103 judges that a sheet is nonreusable, the switching gate
unit 104 chooses a conveying path to the first nonreusable sheet stacker
105.

[0038] The first nonreusable sheet stacker 105 stacks and stores the sheet
P that is judged to be nonreusable by the first judging unit 103.

[0039] The image decolorizing unit 106 is constituted by a pair of
rollers. The pair of rollers generates heat having a temperature equal to
or more than a certain temperature. A sheet having an image formed with
erasable image forming material is passed between the pair of heated
rollers, so that the image is decolorized from the sheet P, and the sheet
P returns back to white. Since the image decolorizing unit 106 is
constituted by the pair of rollers, the images on both sides of the sheet
P can be decolorized.

[0040] The second judging unit 107 is constituted by a pair of
two-dimensional CCD scanners. The CCD scanners scan both sides of a sheet
P to judge whether the image has been decolorized without fault. In other
words, the second judging unit 107 judges whether there is any remaining
image that has not yet been decolorized by the image decolorizing unit
106. In addition, the second judging unit 107 can detect wrinkle, tear,
and the like on the sheet P, which cannot be detected by the sheet
thickness sensor 103b. The second judging unit 107 is not limited to the
pair of two-dimensional CCD scanners, but may be one-dimensional
scanners, CCD sensors, and the like.

[0041] A sheet P that cannot be decolorized, a torn sheet P, and the like
are judged to be nonreusable by the second judging unit 107. The second
nonreusable sheet stacker 108 stacks and stores the sheet P that is
judged to be nonreusable by the second judging unit 107.

[0042] The both sides usable sheet stacker 109 stacks and stores the sheet
P, both sides of which are judged to be reusable by the second judging
unit 107.

[0043] The one-side usable sheet stacker 110 stacks and stores the sheet
P, one side of which is judged to be reusable by the second judging unit
107. In the present embodiment, the upper sides of the sheets P stacked
on the one-side usable sheet stacker 110 are reusable sides. In other
words, the upper sides are white. Alternatively, the sheets P may be
stacked such that the white side of the sheet P is oriented downward.

[0044] The display 111 indicates that sheets are transferred when the
sheet transfer unit 101 transfers sheets. For example, the display 111
turns on an LED to indicate that transfer processing is performed. The
display 111 is not limited to this form. Alternatively, the display 111
may use a display and the like to indicate that the transfer processing
is performed.

[0045] Subsequently, the sheet transfer unit 101 will be explained in
detail. The sheet transfer unit 101 includes the first stacker 200, the
second stacker 201, the partition wall 202, and the pressing unit 203.

[0046] In the sheet transfer unit 101 as shown in FIG. 2, the first
stacker 200 is arranged outside of the decolorizing device 100. The user
stacks sheets P to be reused on the first stacker 200. The user can stack
sheets P on the first stacker 200, even while the decolorizing device 100
is carrying out decolorizing operation of sheets stacked on the second
stacker 201.

[0047] The first stacker 200 includes an upper plate 200a and a lower
plate 200b. A solenoid 204 moves the upper plate 200a upward and downward
via a link mechanism. It is only the first stacker 200 that is
constituted by the upper plate 200a and the lower plate 200b and in which
the upper plate 200a moves upward and downward. The second stacker 201 is
constituted by one plate (tray). Before a sheet P is handed over, the
upper plate 200a is at the same height as the upper surface of the second
stacker 201 or at a height higher than the second stacker 201. When the
sheet P is handed over to the second stacker 201, the upper plate 200a
descends to a height lower than the upper surface of the second stacker
201. After the sheet P has been handed over, and the first stacker 200
returns back to its original position, the upper plate 200a returns back
to the height at which the upper plate 200a was located before the sheet
P was handed over.

[0048] The second stacker 201 is arranged adjacent to the first stacker
200 in the decolorizing device 100. The second stacker 201 is a tray for
stacking the sheets P conveyed from the first stacker 200. The uppermost
sheet P in the bundle of sheets P stacked on the second stacker 201 is
fed one by one by a pickup roller 302a toward the first judging unit 103.
The second stacker 201 ascends and descends within the range of the sheet
feed position with respect to the position adjacent to the first stacker
200. As the uppermost sheet P is fed one by one, the second stacker 201
ascends to such a position that the uppermost sheet P can be smoothly
picked up.

[0049] The partition wall 202 is installed between the first stacker 200
and the second stacker 201, and opens and closes. The partition wall 202
is closed in a normal state. When the sheet P is transferred from the
first stacker 200 to the second stacker 201, the partition wall 202
opens. When the transfer of the sheet P is finished, and the first
stacker 200 returns back to its original position (outside of the
partition wall 202), the partition wall 202 closes.

[0050] The pressing unit 203 is positioned on the upper surface of the
second stacker 201. Even when a sheet P to be reused is curled, the
pressing unit 203 is positioned on the upper surface of the sheet P, so
that the sheet P can be kept flat.

[0051] Hereinafter explained in detail is how a sheet P is transferred
from the first stacker 200 to the second stacker 201. FIG. 2 is a diagram
illustrating the operation of the sheet transfer unit 101. The solenoid
204 and a motor 205 are arranged as a transfer mechanism for transferring
the sheet P from the first stacker 200.

[0052] When the solenoid 204 is activated, the upper plate 200a of the
first stacker 200 descends. Since the upper plate 200a is always urged
upward by a spring, the upper plate 200a ascends back to its original
position when the operation of the solenoid 204 is deactivated. A belt
205c is stretched over a pulley 205b and a motor shaft 205a of the motor
205. The belt 205c rotates, which cause the first stacker 200 coupled
with the belt 205c to move to right and left. The first stacker 200 can
come into proximity to the second stacker 201, and when the partition
wall 202 is open, a portion of the first stacker 200 can enter into the
second stacker 201.

[0053] For the second stacker 201, a motor 206 is arranged as a mechanism
for moving the bundle of sheets P upward and lowering the second stacker
201 back to its original position when the second stacker 201 runs out of
sheet P. A belt 206c is placed over a pulley 206b and a motor shaft 206a
of the motor 206. The belt 206c rotates, which cause the second stacker
201 coupled with the belt 206c to move upward and downward. In FIG. 2,
when the motor 206 rotates in direction t, the second stacker 201
ascends. When the motor 206 rotates in the direction opposite to
direction t, the second stacker 201 descends.

[0054] A motor 207 is used as an open/close mechanism of the partition
wall 202. When the motor 207 rotates, the partition wall 202 coupled with
the motor 207 via the rack moves upward and downward.

[0055]FIG. 3 is a diagram illustrating the sheet transfer unit 101 when
the partition wall 202 is closed. The series of operations will be
hereinafter explained from when the partition wall 202 is closed. How the
sheet P is transferred will be explained on the assumption that sheets P
are stacked on the upper portion of the first stacker 200, which are not
shown in FIG. 3. The second stacker 201 has comb-like projections 201x,
201y, and 201z. The first stacker 200 has concaves 200x, 200y, and 200z
formed respectively corresponding to the projections 201x, 201y, and 201z
of the second stacker 201. When the first stacker 201 moves in the arrow
direction shown in FIG. 5, the concaves 200x, 200y, and 200z of the first
stacker 201 and the projections 201x, 201y, and 201z of the second
stacker 201 engage with each other to form a plate shape.

[0056]FIG. 4 is a diagram illustrating the sheet transfer unit 101 when
the partition wall 202 is open. In FIG. 1, when all the sheets P stacked
on the upper surface of the second stacker 201 have been fed to
processing of later stages, it is necessary to transfer the sheets P on
the first stacker 200. At this occasion, the partition wall 202 changes
from closed state to open state. When it is necessary to transfer the
sheets P from the first stacker 200, the motor 207 of FIG. 2 rotates in
the direction r, which causes the partition wall 202 to ascend.

[0057]FIG. 5 is a diagram illustrating the sheet transfer unit 101 when
the first stacker 200 and the second stacker 201 engage with each other
to form a plate shape as described above. As shown in FIG. 2, the belt
205c is stretched over the pulley 205b arranged on a side face of the
lower plate 200b and the motor shaft 205a of the motor 205. When the
partition wall 202 ascends, the motor 205 rotates in direction s. This
rotation moves the belt 205c, which moves the first stacker 200 toward
the right side of the drawing to a position at which the first stacker
200 engages with the second stacker 201. At this occasion, the sheets P
are positioned on the upper surface of the position at which the first
stacker 200 and the second stacker 201 engage with each other.

[0058]FIG. 6 is a diagram illustrating the sheet transfer unit 101 when
the first stacker 200 has moved downward. When the first stacker 200 and
the second stacker 201 engage with each other, the solenoid 204 as shown
in FIG. 2 is activated, and the upper plate 200a of the first stacker 200
descends. At this occasion since the upper plate 200a of the first
stacker 200 descends, the sheets P are left on the second stacker 201. As
a result, the sheets P are moved from the first stacker 200 to the second
stacker 201.

[0059]FIG. 7 is a diagram illustrating the sheet transfer unit 101 after
the sheets P have been transferred. When the upper plate 200a of the
first stacker 200 descends, the motor shown in FIG. 2 rotates in the
direction opposite to direction s. This rotation moves the belt 205c,
which moves the first stacker 200 to the outside of the partition wall
202. At this occasion, the sheets P are stacked on the second stacker
201, and no sheets P are stacked on the first stacker 200.

[0060]FIG. 8 is a diagram illustrating the sheet transfer unit 101 when
the first stacker 200 moves upward. When the first stacker 200 moves to
the outside of the partition wall 202, the motor 207 of FIG. 2 rotates in
the direction opposite to direction r, and the partition wall 202
descends. Thereafter, when the solenoid 204 is deactivated, the force of
the spring exerts on the upper plate 200a to cause the upper plate 200a
to ascend back to its original position.

[0061] The series of operations of sheet transfer from the first stacker
200 to the second stacker 201 has been hereinabove explained. When the
second stacker 201 runs out of sheet P again, and it is necessary to
transfer sheets P from the first stacker 200, the flow from FIG. 3 to
FIG. 8 is carried out again.

[0062] In the present embodiment, the upper plate 200a of the first
stacker 200 moves upward and downward and to right and left, thereby
handing over the sheets P from the first stacker 200 to the second
stacker 201. Alternatively, the second stacker 201 may move upward and
downward when the sheets P are handed over. In other words, after the
first stacker 200 and the second stacker 201 engage with each other in
FIG. 5, the second stacker 201 is raised, and the sheets P are moved from
the first stacker 200 to the second stacker 201.

[0063] Subsequently, the pressing unit 203 will be explained. FIG. 9 is a
diagram illustrating the second stacker 201 when the uppermost sheet P
stacked on the second stacker 201 is not in contact with a pressing unit
203. The pressing unit 203 includes a pressing face 300, a spring 301, a
pickup unit 302, and an upper surface detecting sensor 303.

[0064] The pressing face 300 for pressing the sheets is arranged to keep
the sheets flat even when the sheets P are curled. The flat face of the
pressing face 300 that is in contact with the sheets P is made of a
low-frictional material. A low-frictional material such as mylar, i.e., a
sheet made of resin, may be attached.

[0065] The spring 301 is arranged at an end of the pressing face 300, and
urges the pressing face 300 in the downward direction of the drawings.
Three or four springs 301 are preferably arranged.

[0066] The pickup unit 302 includes an arm 302c, a spindle 302b rotatably
supporting the arm 302c, and a pickup roller 302a attached to an end of
the arm 302c. The pickup unit 302 is urged downward by a spring. The
pickup roller 302a picks up and feeds the sheets P with the contacting
force and the rotational force exerted on the sheets P. The pickup roller
302a rotates about the spindle 302b.

[0067] The rear end of the arm 302c rotates, and the upper surface
detecting sensor 303 detects the upper surface position of the sheets P
by determining whether the rear end of the arm 302c has blocked a light
passing portion of the sensor 303 or not. When the light passing portion
of the upper surface detecting sensor 303 is blocked by the rear end of
the arm 302c, the upper surface of the sheets P is in contact with the
pressing face 300.

[0068] In FIG. 9, when the uppermost sheet P stacked on the second stacker
201 is not in contact with the pressing unit 203, the pickup roller 302a
rotates about the spindle 302b in the direction opposite to direction u.
At this occasion, light passes through the light passing portion of the
upper surface detecting sensor 303.

[0069] FIG. 10 is a diagram illustrating the second stacker 201 when the
uppermost sheet P stacked on the second stacker 201 is in contact with
the pressing unit 203. The second stacker 201 ascends, and the uppermost
sheet P comes in contact with the pickup roller 302a. In other words,
after the uppermost sheet P comes in contact with the pressing face 300,
the pressing face 300 and the pickup unit 302 are urged upward.
Thereafter, the second stacker 201 is raised. As a result, the pickup
roller 302a rotates about the spindle 302b in direction u. At this
occasion, any light passing through the light passing portion of the
upper surface detecting sensor 303 is blocked by the rear end of the arm
302c. When the light is blocked, the upper surface detecting sensor 303
judges that the sheets P are located at a position raised by a prejudged
amount, and stops the second stacker 201.

[0070] After the ascend of the second stacker 201 has stopped, the pickup
unit 302 conveys the sheets P to processing of later stage. Since the
pressing face 300 is made of a low-frictional material, the sheets P can
be conveyed by the pickup unit 302 and the sheet feed roller 102.

[0071] The upper surface portion of the stacked sheets P is urged downward
by the pressing unit 203, and the stacked sheets P are held by the second
stacker 201 arranged below. Therefore, even when the sheets P are curled,
the sheets P can be held flat. Since the pickup roller 302a is used to
detect the upper surface of the sheets P, the pickup roller 302a can
always feed the sheets P with a constant contacting force.

[0072]FIG. 11 is a top view illustrating the pressing face 300. The
vertical direction of the pressing face 300 of FIG. 11 is a sub-scanning
direction (moving direction of the sheets P). The upper surface of the
pressing face 300 is arranged with a cutout portion 300a through which
the pickup roller 302a is exposed to a portion of the face. When the
pickup roller 302a presses the sheets P, the pickup roller 302a is at a
sheet-pressing pickup roller position 300b. When the second stacker 201
is at a lower level, and the pickup roller 302a is not in contact with
the sheet P, the pickup roller 302a is at a sheet-pressing pickup roller
position 300c.

[0073]FIG. 12 is a top view illustrating the pressing face 300 arranged
with a plurality of cutout portions 300a through which the pickup roller
302a is exposed. In FIG. 12, two cutout portions 300a through which the
pickup roller 302a is exposed are arranged. Alternatively, three or more
cutout portions 300a may be arranged. However, when the pressing face 300
is one plate, it is necessary to arrange the same number of pickup units
300 as the number of cutout portions 300a through which the pickup
rollers 302a are exposed. When a plurality of pickup units 300 are
arranged, the sheets P can be provided in a more stable manner.

[0074] Subsequently, the series of movements of the sheet P in the
decolorizing device 100 will be explained. In the present embodiment,
there are five conveying paths of the sheets P. The first path is used
when the first judging unit 103 judges that the sheet P is nonreusable,
and the sheep P is stored to the first nonreusable sheet stacker 105
through this path. The second path is used when the second judging unit
107 judges that the sheet P is nonreusable, and the sheep P is stored to
the second nonreusable sheet stacker 108 through this path. The third
path is used when the second judging unit 107 judges that the sheet P is
reusable, and the sheep P is stored to the both sides usable sheet
stacker 109 through this path. The fourth path is used when the second
judging unit 107 judges that the upper side of the sheet P is reusable,
and the sheep P is stored to the one-side usable sheet stacker 110
through this path. The fifth path is used when the second judging unit
107 judges that the lower side of the sheet P is reusable, and the sheep
P is stored to the one-side usable sheet stacker 110 through this path.

[0075] First, the first path will be explained. FIG. 13 is a diagram
illustrating the path for a sheet P which is folded and judged to be
nonreusable, and is conveyed to the first nonreusable sheet stacker 105
through this path. Sheets Pa placed on the first stacker 200 are
transferred to the second stacker 201 by the user according to the flow
explained in FIG. 3 to FIG. 8. The display 111 indicates that the sheets
Pa are being transferred while the sheets Pa are transferred. The
transferred sheets Pa are fed to the conveying path by the pickup roller
302a and the sheet feed roller 102. The first judging unit 103 judges
whether the sheet P is overlapped, folded, torn, or the like on the
sheets Pa fed from the second stacker 201. In this example, the sheet Pa
is folded, and is judged by the first judging unit 103 to be nonreusable.
When the first judging unit 103 judges that the sheet Pa is nonreusable,
a switching gate 104a is switched so that the sheet Pa is conveyed to the
first nonreusable sheet stacker 105. The sheet Pa is stored to the first
nonreusable sheet stacker 105. In this example, the sheet Pa is folded,
but the sheet P passes the same path when the sheet P is overlapped or
torn.

[0076] Subsequently, the second path will be explained. FIG. 14 is a
diagram illustrating a conveyance path for a sheet Pb both sides of which
are judged to be non-erasable. In this example, both the front side Pb-1
of the sheet and the back side Pb-2 of the sheet have images formed with
non-erasable image forming material. In the below explanation, the
non-erasable sheet Pb is used. The second path is the same as the first
path up to the judging made by the first judging unit 103, and the
description thereabout is omitted. When the sheet Pb is not folded or the
like, and is judged by the first judging unit 103 to be reusable, the
switching gate 104a is switched so that the sheet Pb is conveyed to the
image decolorizing unit 106. The image decolorizing unit 106 heats the
sheet Pb so as to decolorize the image formed with erasable image forming
material. After the image decolorizing processing, the second judging
unit 107 judges whether the image decolorizing unit 106 has completely
decolorized the image from the sheet Pb and whether the sheet Pb has
returned back to white. In this example, since both sides of the sheet Pb
have images formed with non-erasable image forming material, and the
second judging unit 107 judges that both sides of the sheet Pb are
nonreusable. When the second judging unit 107 judges that both sides are
nonreusable, the switching gate 104a is switched so that the sheet Pb is
conveyed to the second nonreusable sheet stacker 108, and the sheet Pb is
stored to the second nonreusable sheet stacker 108.

[0077] The second judging unit 107 judges that both sides of the sheet P
are nonreusable, not only in the case where the images are formed with
non-erasable image forming material, but also in the following cases: a
note is written to the sheet P with a pen or pencil; a wrinkle occurs on
the sheet P beyond repair; and the sheet P is torn.

[0078] Subsequently, the third path will be explained. FIG. 15 is a
diagram illustrating a conveyance path for a sheet Pc both sides of which
are judged to be erasable. In this example, both of the front side Pc-1
and the back side Pc-2 of the sheet Pc are erasable. The third path is
the same as the second path up to the judging made by the second judging
unit 108, and the description thereabout is omitted. Since the images
formed on both sides of the sheet Pc are formed with erasable image
forming material, the image decolorizing unit 106 decolorizes the images,
and the second judging unit 107 judges that both sides of the sheet P are
reusable. When the second judging unit 107 judges that both sides of the
sheet Pc are reusable, switching gate 104b and 104c are switched so that
the sheet Pc is conveyed to the both sides usable sheet stacker 109, and
the sheet P is stored to the both sides usable sheet stacker 109. The
sheet Pc both sides of which are reusable is not limited to the case
where the images are formed on both sides of the sheet Pc with the
erasable image forming material. Alternatively, an image may be formed on
one side of the sheet Pc with the erasable mage forming material, and no
image may be formed on the other side of the sheet Pc (white side).

[0079] Subsequently, the fourth path will be explained. FIG. 16 is a
diagram illustrating a conveyance path for a sheet Pd only the front side
Pd-1 of which is judged to be erasable. In this example, the front side
Pd-1 of the sheet Pd is erasable, and the back side Pd-2 of the sheet Pd
is non-erasable. The fourth path is the same as the third path up to the
judging made by the second judging unit 108, and the description
thereabout is omitted. Since the front side Pd-1 of the sheet Pd is
erasable and the back side Pd-2 of the sheet Pd is non-erasable, the
second judging unit 107 judges that the front side Pd-1 of the sheet Pd
is reusable. When the second judging unit 107 judges that only the front
side Pd-1 of the sheet Pd is reusable, a switching gate 104d is switched
so that the sheet Pd is conveyed to the one-side usable sheet stacker
110. In other words, in the case where the front side Pd-1 of the sheet
Pd is reusable, the sheet Pd is conveyed via the path indicated by arrow
p and is stored to the one-side usable sheet stacker 110.

[0080] Subsequently, the fifth path will be explained. FIG. 17 is a
diagram illustrating a conveyance path for a sheet Pe only the back side
Pe-2 of which is judged to be erasable. In this example, the front side
Pe-1 of the sheet Pe is non-erasable, and the back side Pe-2 of the sheet
Pe is erasable. The fifth path is the same as the third path up to the
judging made by the second judging unit 107, and the description
thereabout is omitted. Since the front side Pe-1 of the sheet Pe is
non-erasable and the back side Pe-2 of the sheet Pe is erasable, the
second judging unit 107 judges that the back side Pe-2 of the sheet Pe is
reusable. When the second judging unit 107 judges that only the back side
Pe-2 of the sheet Pe is reusable, the switching gate 104d is switched so
that the sheet Pe passes through the path indicated by arrow q. The sheet
Pe proceeding along the path indicated by arrow q is switched back, and
passes through a switching gate 104e, so that the sheet Pe is reversed
and conveyed into the one-side usable sheet stacker 110. In other words,
in the case where the back side Pe-2 of the sheet Pe is reusable, the
sheet Pe is reversed via the reversing path indicated by arrow q and is
stored to the one-side usable sheet stacker 110. That is, the reusable
side of the sheet Pe is actively arranged in the same direction in the
path q. As a result, the sheets Pe stacked on the one-side usable sheet
stacker 110 are uniformly arranged such that the upper side is reusable.

[0081] As shown in FIG. 18, the above-explained decolorizing device 100 is
controlled by a controller 115 having a ROM storing a program. The
controller 115 is connected to each of the first judging unit 103, the
second judging unit 107, the image decolorizing unit 106, the display
111, conveyance motors for driving the conveyance paths, the switching
gates 104a to 104e for switching the paths through which the sheets are
conveyed to the discharge units. Further, the controller 115 is connected
to each of the motor 205 for moving the first stacker 200, the motor 206
for moving the second stacker 201, the motor 207 for opening and closing
the partition wall 202, a feeding motor for feeding sheets P from the
second stacker 201, and the solenoid 204 for moving the upper plate 200a
of the first stacker 200.

[0082] The above-explained decolorizing device can improve the operability
by allowing the user to add sheets P to the first stacker 200 even while
the decolorizing device is carrying out the decolorizing processing.
Further, the decolorizing device includes the pressing unit 203 above the
second stacker 201. The pressing unit 203 keeps sheets P flat and
provides the sheets P in a stable manner even when the sheets P are
curled.

[0083] While certain embodiments have been described, those embodiments
have been presented by way of example only, and are not intended to limit
the scope of the inventions. Indeed, the novel methods and apparatuses
described herein may be embodied in a variety of other forms;
furthermore, various omissions, substitutions and changes in the form of
the methods and apparatuses described herein may be made without
departing from the spirit of the inventions. The accompanying claims and
their equivalents are intended to cover such forms or modifications as
would fall within the scope and spirit of the inventions.